(1) Field of the Invention:
The present invention relates to catalyst carriers made of a metallic material (hereinafter referred to as "metallic catalyst carriers") to be used for purification catalysts to purify combustion waste gases exhausted from automobiles, factories, etc. The invention also relates to a process for producing such catalyst carriers.
(2) Related Art Statement:
Heretofore, Japanese Pat. Application Laid-open No. 56-96,726 discloses a technique using, as a metallic catalyst carrier, a foil made of an aluminum-containing ferrite type stainless steel in which alumina whiskers are formed on surfaces of the foil through heat treatment. According to this technique, a stainless steel which can withstand high temperatures is used, and the alumina whiskers are present on its surface. Therefore, when a catalyst such as .gamma.-Ae.sub.2 O.sub.3 is carried on such a catalyst carrier as a wash coat, the alumina whiskers function as wedges. Thus, the wash coat made of the catalyst such as .gamma.-Ae.sub.2 O.sub.3 can firmly be bonded to the metallic catalyst carrier.
However, in the catalyst carrier disclosed in Japanese Pat. Application Laid-open No. 56-96,726, since the ferrite type stainless steel as a substrate contains aluminum, its plastic deformability is much lower. Thus, it takes many steps to obtain a foil of the stainless steel of this kind, which makes mass production difficult.